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P0871






P0871-OD PRESSURE SWITCH RATIONALITY





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission system uses five pressure switches to monitor the fluid pressure in the L/R, 2C, 4C, UD, and OD clutch circuits. The pressure switches are continuously monitored for the correct states in each gear as shown.

- When Monitored:
Continuously with the ignition on and engine running.

- Set Condition:
The appropriate DTC is set if one of the pressure switches are open or closed at the wrong time in a given gear.





Always perform the Pre-Diagnostic Troubleshooting Procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.






1. CHECK DTCS
1. With the scan tool, read DTCs.

Are there any TCM Power Input DTCs present?

Yes

- Testing and InspectionPerform the appropriate diagnostic procedure.

No

- Go To 2

2. CHECK FOR LINE PRESSURE DTCS
1. With the scan tool, read DTCs.

Are there any Line Pressure DTCs present?

Yes

- Testing and InspectionPerform the appropriate diagnostic procedure.

No

- Go To 3

3. CHECK FOR OTHER PRESSURE SWITCH DTCS
1. With the scan tool, check Transmission DTCs.

Are there two or more other pressure switch rationality DTCs present in addition to P0871?

Yes

- Go To 5

No

- Go To 4

4. CHECK IF DTC IS CURRENT
1. With the scan tool, check and record the Event Data.

NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.

Does the Event Data show data for P0871?

Yes

- Go To 8

No

- Testing and InspectionPerform the appropriate diagnostic procedure.

5. CHECK IF PRESSURE SWITCHES READ CLOSED
1. With the scan tool, check and record the Event Data.

NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.

Do all the pressure switches read CLOSED in the Event Data?

Yes

- Perform the diagnostic procedure for P0882. P0882 Follow instructions as if the DTC is current.

No

- Go To 6

6. CHECK IF PRESSURE SWITCHES READ OPEN

In the Event Data recorded earlier, do all the pressure switches read open?

Yes

- Go To 7

No

- Go To 8

7. CHECK FOR LOW LINE PRESSURE

In the Event Data recorded earlier, is the Line Pressure less than 40 psi, and significantly below the Desired Line Pressure?

Yes

- Repair as necessary to correct low line pressure. Check fluid level and adjust as necessary. If fluid level is OK, check the Primary Oil Filter weal for a spit, crack , or improperly installed. If the filer and seal are OK, check the Main Regulator Valve in the Oil Pump. Refer to the Service Information for the above procedures.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

8. CHECK IF IN DTC SET IN PARK, NEUTRAL, OR REVERSE

In the Event Data recorded earlier, does the Event Data show the OD Pressure Switch DTC set while in Park, Neutral, or Reverse?

Yes

- Go To 18

No

- Go To 9

9. CHECK IF THE OD PRESSURE SWITCH IS OPEN

In the Event Data recorded earlier, did the OD Pressure Switch read OPEN?

Yes

- Go To 10

No

- Go To 15

10. CHECK FOR LOW LINE PRESSURE

In the Event Data recorded earlier, is the Line Pressure less than 40 psi, and significantly below the Desired Line Pressure?

Yes

- Repair as necessary to correct low line pressure. Check the fluid level. Check the Primary Oil Filter seal for a split, crack, or improperly installed. Refer to the Service Information for the proper installation procedure. If the fluid level and filter are OK, check the Main Regulator Valve in the Oil Pump.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 11

11. CHECK THE (T9) OD PRESSURE SIGNAL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT




1. Turn the ignition off to the lock position.
2. Disconnect all PCM harness connectors.
3. Disconnect the Transmission Solenoid/TRS Assembly harness connector.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance between the (T9) OD Pressure Signal circuit and all other circuits in the Transmission Solenoid/TRS Assembly harness connector.

Is the resistance below 5.0 Ohms between the (T9) OD Pressure Signal circuit and any other circuit(s) in the Transmission Solenoid/TRS Assembly harness connector?

Yes

- Repair the (T9) OD Pressure Signal circuit for a short to another circuit(s).
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 12

12. CHECK IF THE DTC RESETS
1. Reconnect all previously disconnected connectors.
2. With the scan too, erase transmission DTCs.
3. Test drive the vehicle, use the Event Data recorded earlier to help duplicate the conditions when the DTC originality set.

Does the DTC P0871 reset?

Yes

- Go To 13

No

- Go To 22

13. CHECK THE POWERTRAIN CONTROL MODULE (PCM)
1. Remove the Transmission Control Relay.
2. Operate the vehicle in Drive.

Is the transmission slipping while in Drive?

Yes

- Go To 14

No

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the and program PCM. With the scan tool, perform Quick Learn. Quick Learn Procedure
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

14. CHECK INTERNAL TRANSMISSION
1. Perform an Air Check Transmission Clutch Operation procedure. Air Checking Transmission Clutch Operation

NOTE: The OD/Rev piston contains a small bleed orifice, a small amount of leakage between the OD and Reverse hydraulic clutch circuits is considered normal.

Is there excessive air leakage in any clutch circuit?

Yes

- Check the OD/Rev piston seals and bleed orifice, reaction shaft support seal rings, dribbler orifice assemblies in the reaction shaft support and for poor machine on the pump valve body faces. Refer to the Service Information.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Repair the Valve Body. Check the OD Accumulator piston and seals, OD bleed orifice, and No. 6 check ball cuts or damage. If no problems are found in the Valve Body, replace the Transmission Solenoid/TRS Assembly. Refer to the Service Information for proper repair procedures.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

15. CHECK PCM AND WIRING
1. Turn the ignition off to the lock position.
2. Remove the Starter Relay.

CAUTION: Removal of the Starter Relay will prevent the vehicle from being started in gear.

WARNING: The Starter Relay must be removed from the PDC. Failure to do so may result in possible serious or fatal injury.

NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.

3. Install Transmission Simulator 8333.
4. Ignition on, engine not running.
5. With the Transmission Simulator, turn the Pressure Switch selector switch to OD.
6. With the scan tool, monitor the OD Pressure Switch state while pressing the Pressure Switch Test button on the Transmission Simulator.

Did the state of the OD Pressure Switch change from OPEN to CLOSED while pressing the Test button?

Yes

- Go To 16

No

- Go To 18

16. CHECK IF THE NO. 4 AND/OR NO. 6 CHECK BALL IS CUT OR DAMAGED
1. With the scan tool, erase previously stored DTCs and test drive the vehicle, use the Event Data to help duplicate the conditions when the DTC originality set. Note any DTCs that may set.
2. Remove the Transmission Valve Body.
3. Check the No. 4 and No. 6 Check Balls for cuts or damage.

Is the No. 4 and/or No. 6 Check Ball cut or damaged?

Yes

- Replace the No. 4 and/or No. 6 Check Ball and check for clutch debris in the transmission oil pan. If there is excessive debris, perform internal repairs to the OD Clutch Assembly. Refer to the Service Information for proper repair procedures.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 17

17. TRANSMISSION SOLENOID/TRS ASSEMBLY

Did the DTC P0871 reset during the test drive in the previous step?

Yes

- Replace the Transmission Solenoid/TRS Assembly.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 22

18. CHECK THE (T9) OD PRESSURE SIGNAL CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Disconnect the PCM C4 harness connector and connect the PCM Pinout Box 8815.
3. Disconnect the Transmission Solenoid/TRS Assembly harness connector

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box 8815 to perform diagnosis.

4. Measure the resistance of the (T9) OD Pressure Signal circuit between the Solenoid/TRS Assembly harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (T9) OD Pressure Signal circuit for an open.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 19

19. CHECK THE (T9) OD PRESSURE SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (T9) OD Pressure Signal circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (T9) OD Pressure Signal circuit for a short to ground.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 20

20. CHECK WIRING AND CONNECTORS
1. Using the schematics as a guide, inspect the wiring and connectors. Pay particular attention to all power and ground circuits.

Were there any problems found

Yes

- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 21

21. CHECK IF DTC RESETS
1. Reconnect all previously disconnected connectors.
2. Make sure all Event Data is recorded.
3. With the scan tool, erase previously stored DTCs and test drive the vehicle, use the Event Data to help duplicate the conditions when the DTC originality set.

Does the DTC P0871 reset?

Yes

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the PCM. With the scan tool, perform Quick Learn. Quick Learn Procedure
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Go To 22

22. CHECK WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

Where there any problems found?

Yes

- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test

No

- Test Complete.

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